Processors are circuits that can process tasks, code, middleware, and the like and are characterized by power consumption changes. Non-limiting examples of processors include general purpose processors, digital signal processors, controllers, direct memory access controllers and the like.
Processors can be characterized by fast power consumption changes. The power consumption changes can result from turning on the processor or some of the circuits of the processor, as well as changes in the computational loads of the processor.
The processor and more exactly the integrated circuit that includes the processor receive a supply voltage from a voltage source. The supply voltage is provided via a supply network that may include capacitors. Fast changes in the power consumption of the processor can result in a voltage drop—a reduction of the supply voltage provided to the processor. This reduction can result in a provision of a supply voltage that is lower than a level required for the operation of the processor. The voltage drop can occur due to the relatively slow response of the voltage source and, additionally or alternatively from the supply network and especially the bypass capacitors (C), inductive (L) and resistance (R) elements for supply path on the board, as well as parasitic RLC elements.
FIG. 1 schematically illustrates multiple signals.
Curve 1 illustrates the performance (in Million Instructions Per Second—MIPS) of a processor. During a first period (before T1 8) processor operates a low performance mode and its performance is low (P1 2), during a second period (between T1 8 and T2 9) the performance is high (P2 3) and during a third period (after T2 9) the performance is low again (P1 2).
Curve 6 illustrates the current consumption of a processor. The current consumption is correlated with the performance. During the first period (before T1 8) the processor operates in the low performance mode and consumes a low amount of current (I1 4), during the second period (between T1 8 and T2 9) the current consumption is high (I2 5) and during a third period (after T2 9) the current is low again (I1 4).
Curve 7 illustrates the supply voltage that is supplied by a voltage source to a device that includes the processor. Threshold 10 is a minimal value of the supply voltage that should be supplied to the processor in order to allow functional operation. A first event that changes the power consumption of the processor occurs at T1 8 and is followed by a fast increment of the power consumption of the processor and the voltage source recovers from this fast increment only after a regulation period 11 ends. During this regulation period the supply voltage drops (by voltage drop 13) below threshold 10 and causes the processor to malfunction. A second event that changes the power consumption of the processor occurs at T2 9 and is followed by a regulation period 9′ during which the supply voltage is slightly incremented.
Dynamic voltage and frequency scaling (DVFS) technique reduces power consumption of an integrated circuit by increasing the supply voltage level and frequency of a clock signal provided to a processor when the computational load of the computer increases. The reaction time and working time window of this technique is much slower (hundreds and thousands of the clock cycles) and can not be implemented for voltage regulation with resolution of discussed issue.